[Linker] Import IFuncs

[nextsilicon-itay-bookstein]

Summary

When importing symbols from another module, also import GlobalIFuncs.

Author: Itay Bookstein <[e-mail]>

[MaskRay]

llvm/test/Linker/ifunc.ll

2

You can use split-file %s %t to avoid a oneshot temporary file under Inputs/

There are quite a few examples in llvm-project, e.g. in lld/test/ELF

[nextsilicon-itay-bookstein]

Updated the test per @MaskRay 's suggestion.

[MaskRay]

Thanks!

[nextsilicon-itay-bookstein]

I cannot commit the patch myself because I don't have commit access, might I trouble you with that? :)

llvm/lib/Linker/LinkModules.cpp

bool ModuleLinker::run() {
   for (Function &SF : *SrcM)
     if (linkIfNeeded(SF))
       return true;
 
   for (GlobalAlias &GA : SrcM->aliases())
     if (linkIfNeeded(GA))
       return true;
 
+  for (GlobalIFunc &GI : SrcM->ifuncs())
+    if (linkIfNeeded(GI))
+      return true;
+
   for (unsigned I = 0; I < ValuesToLink.size(); ++I) {
     GlobalValue *GV = ValuesToLink[I];
     const Comdat *SC = GV->getComdat();
     if (!SC)
       continue;
     for (GlobalValue *GV2 : LazyComdatMembers[SC]) {
       GlobalValue *DGV = getLinkedToGlobal(GV2);
       bool LinkFromSrc = true;

llvm/test/Linker/ifunc.ll

+; RUN: split-file %s %t
+; RUN: llvm-link %t/a.ll %t/b.ll -S -o - | FileCheck %s
+
+;; Check that ifuncs are linked in properly.
+
+; CHECK-DAG: @foo = ifunc void (), bitcast (void ()* ()* @foo_resolve to void ()*)
+; CHECK-DAG: define internal void ()* @foo_resolve() {
+
+; CHECK-DAG: @bar = ifunc void (), bitcast (void ()* ()* @bar_resolve to void ()*)
+; CHECK-DAG: define internal void ()* @bar_resolve() {
+
+;--- a.ll
+declare void @bar()
+
+;--- b.ll
+@foo = ifunc void (), bitcast (void ()* ()* @foo_resolve to void ()*)
+@bar = ifunc void (), bitcast (void ()* ()* @bar_resolve to void ()*)
+
+define internal void ()* @foo_resolve() {
+  ret void ()* null
+}
+
+define internal void ()* @bar_resolve() {
+  ret void ()* null
+}